(i) Technical Field
The present invention relates to a color processing apparatus and method and a computer readable medium.
(ii) Related Art
Generally, an output apparatus outputs color images by using basic color components, such as cyan (C), magenta (M), and yellow (Y), and red (R), green (G), and blue (B), and such basic color components are necessary for outputting color images. An output apparatus using C, M, and Y as basic color components, for example, may use other color components. A color gamut, which is a range of colors reproduced by an output apparatus, may be represented, not only by basic color components, but also by a black (K) component or by a specific color component, such as an orange (O), green (G), or violet (V) component. By the use of the K component, the brightness becomes lower than that when the color gamut is represented only by the basic color components. By the use of the O, G, or V component, the chroma becomes higher than that when the color gamut is represented only by the basic color components.
When color images are output from an output apparatus, certain conditions (hereinafter called “design conditions”) may be added to some color components or all color components. For example, design conditions, such as the total value of color components is equal to or less than a predetermined maximum total value, may be added. As another example of design conditions, a range of values may be applied to each color component. If such conditions are imposed, the color gamut, which is a range of colors reproduced by an output apparatus, may sometimes be narrower than that when such conditions are not imposed. For example, concerning the above-described K component, there may be some colors that are not possible to reproduce if the K component is not used, and such colors are not reproduced if the use of the K component is restricted by the design conditions for the sake of image quality.
There may also be some cases in which a color represented by a color signal supplied to an output apparatus is not included in the color gamut of the output apparatus. In this case, generally, processing for converting such a color into a color included in the color gamut is performed. In order to perform such conversion processing, it is necessary to determine the boundary of the color gamut, which is an interface between colors that are reproduced by an output apparatus and colors that are not reproduced by the output apparatus.
When design conditions are set, the boundary of the color gamut becomes different depending on the types of design conditions. It is thus necessary to determine the boundary of the color gamut in accordance with set design conditions.